Because they're new to you.
Because if you actually read the books thoroughly, you'd see they aren't actually restrictions, and they're certainly not any different from what a D&D GM does. What they are is a description of your role as GM, codified in a way that previous games rarely did, because in those games, it was just expected you'd figure it out on your own or read Dragon Magazine and pick up stuff from there. Instead, PbtA took all that accumulated wisdom and bullet-pointed it.
Maybe, just maybe, that codified role is something people don't care for. It may be "accumulated wisdom" to you and certainly some of it likely applies to a D&D game, at least from time to time. But it's also very focused on the narrative, pushing the game forward, setting up tough choices. Take the last point - tough choices. Sometimes I throw those in now and then and in other campaigns depending on the group it never comes up. Yet as a GM for many PbtA games that's what you're instructed to do. Along with, of course, resource moves in cases where the characters fail or partially fail.
There's nothing wrong with any of that if it's what you want. But it's not that I don't want it because it's new, that's a derogatory assumption that gets repeated ad-nauseum. I don't want it because I prefer a more simulationist approach whether running a game or playing. I'm glad you have games you enjoy. The assumption we would also enjoy it if only we knew better is insulting.